Lower Extremity Arterial Bypass Research Articles

Endoscopic Vein Harvesting in Lower Extremity Arterial Bypass: A Systematic Review

Endoscopic vein harvesting (EVH) for arterial bypass surgery may be associated with lower wound complication rates than open vein harvesting (OVH), but other long-term outcomes remain controversial, and there are concerns that graft patency may be poorer after EVH compared with OVH. We conducted a systematic review of all available evidence for EVH in lower extremity arterial bypass (LEAB). A literature search of Medline, Embase, Ovid and Cochrane databases between 1996 and 2013 was performed using the terms “endoscopic vein harvesting”, “minimally invasive vein harvest”, “peripheral bypass surgery”, and “lower extremity bypass surgery”, and detailed in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Primary outcomes were graft patency and overall wound complication rates. Secondary outcomes were wound infection, length of hospital stay, and cost-effectiveness. Summary estimates were calculated by random effects meta-analysis if sufficient data were available. We identified 18 cohort studies and case series, with considerable clinical heterogeneity, including 2,343 patients. Meta-analysis of six studies revealed a significantly reduced rate of primary patency after EVH (hazard ratio 1.29, 95% confidence interval [CI] 1.03-1.63), with no significant difference between EVH and OVH with respect to wound infection in 12 studies (odds ratio 0.81, 95% CI 0.61-1.08). There was a lack of strong evidence to support the secondary outcomes of EVH. EVH reduces primary patency rates after LEAB, but does not demonstrate an advantage with respect to postoperative wound complications. However, the available data are heterogeneous, and uncertainty is introduced by both evolution in technology and increasing technical experience. EVH should be used with caution and in the context of formal research.

Reliability of hospital readmission rates in vascular surgery

The Center for Medicare and Medicaid Services recently began assessing financial penalties to hospitals with high readmission rates for a narrow set of medical conditions. Because these penalties will be extended to surgical conditions in the near future, we sought to determine whether readmissions are a reliable predictor of hospital performance with vascular surgery. We examined 4 years of national Medicare claims data from 1576 hospitals on beneficiaries undergoing three common vascular procedures: open or endovascular abdominal aortic aneurysm repair (n = 81,520) or lower extremity arterial bypass (n = 57,190). First, we divided our population into two groups on the basis of operative date (2005-2006 and 2007-2008) and generated hospital risk- and reliability-adjusted readmission rates for each time period. We evaluated reliability through the use of the "test-retest" method; highly reliable measures will show little variation in rates over time. Specifically, we evaluated the year-to-year reliability of readmissions by calculating Spearman rank correlation and weighted κ tests for readmission rates between the two time periods. The Spearman coefficient between 2005-2006 readmissions rankings and 2007-2008 readmissions rankings was 0.57 (P < .001) and weighted κ was 0.42 (P < .001), indicating a moderate correlation. However, only 32% of the variation in hospital readmission rates in 2007-2008 was explained by readmissions during the 2 prior years. There were major reclassifications of hospital rankings between years, with 63% of hospitals migrating among performance quintiles between 2005-2006 and 2007-2008. Risk-adjusted readmission rates for vascular surgery vary substantially year to year; this implies that much of the observed variation in readmission rates is either random or caused by unmeasured factors and not caused by changes in hospital quality that may be captured by administrative data.

Early graft failure after infrainguinal arterial bypass

Early graft failure (EGF), defined as failure within 30 days of an index procedure, is aserious complication after infrainguinal arterial bypass. EGF has not been examined by the use of national data since the widespread adoption of percutaneous treatments for arterial occlusive disease. We used data from the American College of Surgeons National Surgical Quality Improvement Program. Patients who underwent infrainguinal arterial bypass from 2005 to 2011 were selected from the American College of Surgeons National Surgical Quality Improvement Program database. The frequency of 30-day EGF was determined. Univariate and multivariate analyses evaluated risk factors for EGF. Of 23,468 patients who underwent open infrainguinal arterial bypass, 1,065 (4.5%) had EGF. Patients who had EGF were more likely to have a prolonged duration of stay (34.8% vs 12.0%, P< .001), greater rates of reoperation (82.1% vs 14.3%, P < .001) and increased 30-day mortality (5.1% vs 2.1%, P < .001). The rate of additional complications in patients who experienced EGF was 42.0%, compared with 25.4% in those who did not have EGF (P < .001). Patients who experienced complications in addition to EGF were more likely to have complications after graft failure (69.5% vs 31.3%). In multivariable analysis, EGF was associated with younger age, female sex, black race, obesity, thrombocytosis, increased international normalized ratio, femoral-to-tibial bypass, prosthetic graft, and emergent operation. The incidence of EGF after open lower extremity arterial bypass has not increased in an era of increased use of percutaneous techniques. Nevertheless, EGF occurs in almost 5% of patients and is strongly associated with additional complications and mortality. Identifying patients at risk for EGF may facilitate modification of contributing factors. Diminishing the incidence of graft occlusion will lead to decreased morbidity and mortality in this cohort of patients.

Preoperative Arterial Pulse Pressure Has No Apparent Association With Perioperative Mortality After Lower Extremity Arterial Bypass

Survey of Anesthesiology: April 2013 - Volume 57 - Issue 2 - p 103-104 doi: 10.1097/01.SA.0000427311.88065.d8

Volume-Outcome Relationships in Lower Extremity Arterial Bypass Surgery

Volume-Outcome Relationships in Lower Extremity Arterial Bypass Surgery

Volume–Outcome Relationships in Lower Extremity Arterial Bypass Surgery

We sought to investigate whether a volume-outcome relationship exists for lower extremity arterial bypass (LEAB) surgery. All LEAB procedures performed in England between 2002 and 2006 were identified from Hospital Episode Statistics data. A Charlson-type risk profile, including operating hospital annual case volume, was identified per patient. Outcome measures of revision bypass, amputation, death and a composite measure were established during the index admission and at 1 year.Quintile analysis and multilevel multivariate modeling were used to identify the existence of a volume-outcome relationship and allow adjustment of results for significant determinants of outcome. A total of 27,660 femoropopliteal bypass and 4161 femorodistal bypass procedures were identified.As volume increased, in-hospital mortality after popliteal bypass decreased from 6.5% to 4.9% (P = 0.0045), with a corresponding odds ratio of 0.980 [95% confidence interval (CI), 0.929-0.992; P = 0.014] for every increase of 50 patients per year. Major amputation decreased from 4.1% to 3.2% (P = 0.006) in high-volume hospitals, with a reduction in risk of 0.955 (95% CI, 0.928-0.983; P = 0.002) at 1 year.For distal bypass, in-hospital mortality decreased from 9.8% to 5.5% (P = 0.004) and 1-year major amputation decreased from 25.4% to 18.2% (P < 0.001), with a corresponding odds ratio of 0.658 (95% CI, 0.517-0.838; P < 0.0001) as the volume increased.An increase in the chance of revision surgery (10.6% vs 8.2%, P < 0.001) was seen with higher volume, with an increased odds ratio of 1.031 (95% CI, 1.005-1.057; P = 0.018). A positive volume-outcome relationship exists for LEAB procedures even after employing multilevel risk adjustment models. There are benefits in terms of mortality and limb salvage both in the short-term and at 1 year postsurgery.

Computed tomography angiography-based evaluation of great saphenous vein conduit for lower extremity bypass

Lower extremity computed tomography angiography (CTA) is frequently used for anatomic assessment of lower extremity peripheral arterial disease. When lower extremity bypass is planned, duplex ultrasound (DUS) is routinely obtained to evaluate the great saphenous vein (GSV) for use as conduit. Although GSV can be visualized on CTA images, diameter assessment is not routinely included in formal study interpretation. We hypothesized that CTA images could be used to measure GSV diameters and that CTA-based diameters would correlate with measurements obtained using DUS. Consecutive patients undergoing lower extremity arterial bypass who were evaluated preoperatively with both CTA and DUS vein mapping were identified at a single hospital. Minimum above- and below-knee GSV diameters were measured from electronically archived CTA images by two independent observers. CTAs were performed using standard arterial phase protocol without additional venous phase imaging. Between-observer reproducibility of CTA-based diameter measurements was evaluated using intraclass correlation coefficients. Correlation between CTA and DUS-based GSV diameters was evaluated with Spearman correlation coefficients. CTA diameter cut-points for identification of adequate GSV bypass conduit, defined as DUS-based minimum GSV diameter≥3 mm, were determined using receiver-operating characteristic curves. Sixty-three lower extremities were evaluated in 36 patients. In the absence of previous surgical removal, GSV was visible on all CTAs reviewed. No instances of GSV thrombosis were identified on DUS. Minimum DUS-based above-knee GSV diameter was 2.9±0.1 mm (range, 1.4-4.6 mm), and mean below-knee diameter was 2.6±0.1 mm (range, 1.3-4.0 mm). When GSV was visible and exceeded the minimum diameter threshold for CTA measurement, correlation between CTA- and DUS-based diameters was both positive and highly significant (ρ=0.595; P<.0001). CTA-based diameters also had excellent reliability between observers (r [95% CI]: 0.88 [0.85-0.91]). For identification of adequate bypass conduit using CTA, above-knee GSV diameter≥3.9 mm was 67% sensitive and 73% specific; below-knee GSV diameter≥3.0 mm was 75% sensitive and 84% specific. CTA-based GSV diameter measurements have good reproducibility and highly significant correlation with DUS-based diameters. CTA-based GSV diameter is a specific but relatively insensitive indicator of adequate bypass conduit. When CTA-based diameters indicate inadequate GSV bypass conduit, confirmatory DUS vein mapping is warranted. Confirmatory DUS vein mapping may be unnecessary when adequate vein diameter is identified on CTA.

Noncardiac Surgery

Noncardiac Surgery

PS124. Experience with a New Negative Pressure Incision Management System in Prevention of Groin Wound Infection in Vascular Surgery Patients

Groin wound infection is an important cause of postoperative morbidity in vascular surgery patients, especially when prosthetic graft is involved. We report our experience with a new negative pressure incision management system in prevention of groin wound infection following open vascular procedures. The Prevena ™ negative pressure incision management system (Kinetic Concepts, Inc. San Antonio, TX) was used on 53 groin incisions in 41 consecutive patients from December 2010 to December 2011. Twenty-seven were males and 14 were females with mean age 52 (range, 23-76) years. The procedures included lower extremity arterial bypass, femoral artery endarterectomy with patch angioplasty, femoral artery exposure for aortic stentgrafts, and open repair of vascular injury. The Prevena ™ dressing was placed at the end of procedure using sterile technique, and kept in place for 5-7 days. Patients were sent home with Prevena ™ system when discharge criteria were met. Incisions were evaluated immediately after removal of the Prevena ™ dressing and at one month follow-up. Of the 53 groin incisions, 2 were excluded from this study because the Prevena ™ was removed on postoperative day 2 due to air-leaking around the dressings. Thirty-nine of the rest 51 incisions were vertical (76.4%), and 12 were transverse (23.5%). Prosthetic grafts or patches were used in 32 incisions (62.7%). Three incisions developed Szilagyi Grade I cellulitis (5.7%), which healed with 7-day course of oral antibiotics. There was no Szilagyi Grade II or III infection (0%) in all 51 incisions. The Prevena ™ negative pressure incision management system may significantly decrease the rate of Szilagyi Grade II and III groin wound complications and subsequently prevent graft infection following vascular surgery. It is safe, portable, and easy to apply. Patient may ambulate with the negative pressure dressing in place. Follow-up to assess possible late prosthetic graft infection is in progress.

Early Graft Failure After Lower Extremity Arterial Bypass: Results from More Than 200 Hospitals

Early Graft Failure After Lower Extremity Arterial Bypass: Results from More Than 200 Hospitals

Treatment of failing vein grafts in patients who underwent lower extremity arterial bypass

PurposeWe attempted to determine risk factors for the development of failing vein graft and optimal treatment in patients with infrainguinal vein grafts.MethodsWe retrospectively reviewed a database of patients who underwent infrainguinal bypass using autogenous vein grafts due to chronic atherosclerotic arterial occlusive disease of lower extremity (LE) at a single institute between September 2003 and December 2011. After reviewing demographic, clinical, and angiographic features of the patients with failing grafts, we analyzed those variables to determine risk factors for the development of failing grafts. To determine an optimal treatment for the failing vein grafts, we compared results of open surgical repair (OSR), endovascular treatment (EVT) and conservative treatment.ResultsTwo hundred and fifty-eight LE arterial bypasses using autogenous vein grafts in 242 patients were included in this study. During the follow-up period of 39 ± 25 months (range, 1 to 89 months), we found 166 (64%) patent grafts with no restenosis, 41 (15.9%) failing grafts, 39 (15.1%) graft occlusions, and 12 (4.7%) grafts lost in follow-up. In risk factor analysis for the development of a failing graft, no independent risk factors were identified. After 50 treatments of the 41 failing grafts (24 OSR, 18 EVT, 8 conservative management), graft occlusion was significantly more common in conservative treatment group and severe (>75%) restenosis was significantly more common following EVT than OSR (P = 0.001). Reintervention-free graft patency was also superior in the OSR group to that of the EVT group (87% vs. 42%, P = 0.015).ConclusionOSR of failing grafts has better outcomes than EVT or conservative management in treating failing grafts.

Socioeconomic Position Is Not Associated With 30-Day or 1-Year Mortality in Demographically Diverse Vascular Surgery Patients

Disparities in outcomes after surgical procedures have been attributed to race, sex, use of private insurance, and socioeconomic position (SEP). The purpose of this study was to determine the impact of SEP on mortality after lower-extremity bypass (LEB) surgery in a diverse patient population with extremes of SEP. Analysis of an electronic medical database. A tertiary care hospital in a demographically diverse section of a large metropolitan area. Six hundred nine (158 white men, 156 nonwhite men, 100 white women, and 195 non-white women) patients undergoing infrarenal lower-extremity arterial bypass surgery from July 1, 2002, to December 31, 2007. SEP was estimated using data from the 2000 US Census. The effects of race, sex, various comorbidities, the Revised Cardiac Risk Index, American Society of Anesthesiologists physical status, use of private insurance, indication for bypass surgery, and SEP on all-cause mortality was analyzed. SEP differed significantly among the 4 race-sex groups, with white men having the highest position (mean = 2.38) and non-white men having the lowest position (mean = -3.02). There was no statistically significant association in 30-day mortality among race-sex groups or with SEP. One-year mortality differed significantly between men and women for the entire cohort (13.7% and 24.1%, respectively; p < 0.01) but not among race groups or SEP. Disparities in SEP are not associated with short- or long-term mortality after LEB surgery. Other comorbid risk factors are more important when determining outcomes and should be the focus of interventions to improve outcomes.

Preoperative Arterial Pulse Pressure Has No Apparent Association with Perioperative Mortality After Lower Extremity Arterial Bypass

Arterial pulse pressure hypertension is associated with perioperative morbidity and mortality in cardiac surgery patients. However, its association with perioperative mortality in other high-risk surgical populations has not been determined. In this study, we tested the hypothesis that increased preoperative arterial pulse pressure is associated with 30-day and 1-year all-cause mortality after lower extremity arterial bypass surgery. A retrospective review of patients who had infrainguinal arterial bypass surgery at a single center over a 6-year period (January 2002 to January 2008) was performed (n = 556). Mean, systolic, and diastolic arterial blood pressure were determined from a single noninvasive oscillometric blood pressure cuff reading in the operating room before the administration of anesthetic drugs. Pulse pressure was calculated from this measurement in a retrospective manner by subtracting diastolic pressure from systolic pressure. Mortality for all subjects was determined using the social security death index. Comorbid conditions, preoperative medications, and anesthetic techniques were recorded. Univariate and multivariate analyses were performed to evaluate the association between arterial pulse pressure and the primary outcome variables, and all-cause 30-day and 1-year mortality. Of the 556 patients, a large percentage had elevated pulse pressure (44.9% had pulse pressure ≥80). Thirty-day mortality was 5.1% and 1-year mortality was 17.8%. There was no apparent association between preoperative pulse pressure and 30-day (P = 0.35) or 1-year (P = 0.14) all-cause mortality. Independent predictors of 30-day mortality were age ≥80 years (P = 0.02), ASA physical status ≥IV (P = 0.04), baseline creatinine >2.0 mg/dL (P < 0.0001), and emergency surgery (P = 0.009). The same variables were associated with 1-year mortality, as were the Lee's Revised Cardiac Risk Index score, female gender, and gangrene or ulcer as an indication for surgery. Our results suggest that increased preoperative arterial pulse pressure might not be associated with all-cause mortality after lower extremity arterial bypass surgery.

Predictors of surgical site infection after open lower extremity revascularization

Surgical site infection (SSI) after open surgery for lower extremity revascularization is a serious complication that may lead to graft infection, prolonged hospitalization, and increased cost. Rates of SSI after revascularization vary widely, with most studies reported from single institutions. The objective of this study was to describe the rate and predictors of SSI after surgery for arterial occlusive disease using national data, and to identify any association between SSI and length of hospital stay, reoperation, graft loss, and mortality. Patients who underwent lower extremity arterial bypass or thromboendarterectomy from 2005-2008 were identified from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) participant use files. Multivariate logistic regression identified predictors of SSI. Odds ratios were adjusted for patient demographics, comorbidities, preoperative laboratory values, and operative factors. The association between SSI and other 30-day outcomes such as mortality and graft failure was determined. Of 12,330 patients who underwent revascularization, 1367 (11.1%) were diagnosed with an SSI within 30 days. Multivariate predictors of SSI included female gender (odds ratio [OR], 1.4; 95% confidence interval [CI], 1.3-1.6), obesity (OR, 2.1; 95% CI, 1.8-2.4), chronic obstructive pulmonary disease (OR, 1.2; 95% CI, 1.0-1.5), dialysis (OR, 1.5; 95% CI, 1.1-2.1), preoperative hyponatremia (OR, 1.2; 95% CI, 1.0-1.4), and length of operation >4 hours (OR, 1.4; 95% CI, 1.2-1.6). SSI was associated with prolonged (>10 days) hospital stay (OR, 1.8; 95% CI, 1.4-2.1) and higher rates of 30-day graft loss (OR, 2.3; 95% CI, 1.7-3.1) and reoperation (OR, 3.7; 95% CI, 3.1-4.6). SSI was not associated with increased 30-day mortality. SSI is a common complication after open revascularization and is associated with a more than twofold increased risk of early graft loss and reoperation. Several patient and operation-related risk factors that predict postoperative SSI were identified, suggesting that targeted improvements in perioperative care may decrease complications and improve outcomes in this patient population.

Transit-Time Volume Flow Measurements in Autogenous Femorodistal Bypass Surgery for Intraoperative Quality Control

The aim of this study was to assess intraoperative transit-time volume flow measurements (VFMs) as a tool for intraoperative evaluation of lower extremity arterial bypass grafts and to predict their patency. We analyzed 273 consecutive patients who had an infrainguinal bypass procedure using the great saphenous vein from 1998 until 2008; 103 had an intraoperative VFM. All intraoperative revisions were recorded and analyzed. Patency and revision rates were compared between those receiving and those not receiving intraoperative VFM. Cox regression was used for analysis of predictors of patency. Primary patency at 1 and 2 years was 75 and 67%, respectively, in patients receiving intraoperative VFM versus 72 and 69% in those without VFM (p = .79). In the VFM group, 12% had an immediate revision versus 6% without VFM (p = .06). In the VFM group, 4% underwent revision to salvage the bypass within the first postoperative 30 days versus 6% without VFM (p = .32). Patency was not associated with the use of VFM. Receiver operating characteristic curve was significant for occlusion at 30 days postoperatively but with a low predictive value (p = .019,area under the curve 0.648). VFM may be helpful in selecting bypasses requiring immediate revision to prevent postoperative occlusion. The use of VFM is not significantly associated with patency.

The Effect of Immunosuppression on Lower Extremity Arterial Bypass Outcomes

Myointimal hyperplasia is a pathologic result of the body's natural inflammatory response to injury of the blood vessels and a leading cause of peripheral arterial bypass failure. Because immunosuppressive agents are known to abate inflammation, we hypothesized the superior outcome of lower extremity bypass in renal transplant recipients compared with the hemodialysis population. The vascular surgery registry at a single tertiary care center was retrospectively reviewed to identify patients who underwent lower extremity bypass procedures. All patients with a history of renal transplantation were selected for analysis. A consecutive group of bypass patients with dialysis-dependent renal failure was selected as a control cohort. The primary endpoint was amputation-free survival. Vascular reconstruction for chronic peripheral vascular disease yielded an amputation-free survival rate of 82% at 1 year for the those in the control group as compared with only 22% in the those with a history of renal transplantation (p = 0.02), which corresponded exactly with primary patency at 1 year. Patients were operated on for severe claudication (n = 1), rest pain (n = 1), and tissue loss (n = 17). There was no difference between the groups with regard to indication for operation or comorbid conditions. These data suggest a deleterious effect of immunosuppression on outcome of lower extremity bypass procedures at the doses required to prevent allograft rejection. This finding, which has been scarcely reported, underscores the importance of peripheral vascular disease screening in the transplant population and early intervention when clinically indicated.

Limb Salvage With CryoVein Cadaver Saphenous Vein Allografts Used for Peripheral Arterial Bypass: Role of Blood Compatibility

Patients suffering from limb-threatening ischemia often have scarce or inadequate autogenous veins for complex lower limb revascularization. One option for such patients is to use conduit consisting of cadaver saphenous vein allograft (CSVA) as a final surgical option before limb amputation. This study reviewed retrospectively the patency of CryoVein CSVA allografts, processed by CryoLife, Inc., in 54 implant cases of lower extremity arterial bypass over a span of 6 years. Patient demographics, graft patency, limb salvage, and blood type matching of donor to recipient were analyzed. Kaplan-Meier analysis showed postoperative primary patency rates of 89, 63%, 30%, 17%, and 9% at 1, 3, 6, 12, and 18 months, respectively. Secondary patency rates were 89%, 74%, 63%, 63%, and 54% at 1, 3, 6, 12, and 18 months, respectively. Limb salvage rates were 67% at 12 months and 54% at 18 months. Median follow-up was 467 days. Of the 34 cases where the patient received a blood-group compatible CSVA, 30 had limb salvage and only six of 20 noncompatible grafts offered limb salvage (p = 0.05). Although primary patency rate was poor at 1 year, high secondary patency and limb salvage rates support the use of CSVA as a peripheral bypass conduit alternative. Cases with donor-recipient ABO blood type compatibility had significantly better limb salvage.

Volume-Outcome Relationships in Vascular Surgery: The Current Status

Vascular surgery has been widely practiced in hospitals within a general surgical service, although the consequent workload of individual vascular units has been small. There is an increasing body of evidence in favor of a positive relationship between hospital and surgeon volumes and the outcome of arterial surgery. These relationships suggest that vascular surgical procedures might be best placed within a centralized model of care to increase volume and thereby attain best outcomes. This systematic review appraises the current evidence for volume-outcome relationships in vascular surgery from a number of healthcare systems to examine the basis for centralization of vascular surgical services. The index procedures addressed in this review are open or endovascular repair of abdominal aortic aneurysm (AAA), ruptured AAA, descending thoracic aortic aneurysm, and thoracoabdominal aortic aneurysm, along with carotid endarterectomy and lower extremity arterial bypass.

Functional adaptation of venous smooth muscle response to vasoconstriction in proximal, distal, and varix segments of varicose veins

Varicose veins (VarVs) are a common disorder of venous dilation and tortuosity with unclear mechanism. The functional integrity and the ability of various regions of the VarVs to constrict is unclear. This study tested the hypothesis that the different degrees of venodilation in different VarV regions reflect segmental differences in the responsiveness to receptor-dependent vasoconstrictive stimuli and/or in the postreceptor signaling mechanisms of vasoconstriction. Varix segments and adjacent proximal and distal segments were obtained from patients undergoing VarV stripping. Control great saphenous vein specimens were obtained from patients undergoing lower extremity arterial bypass and coronary artery bypass grafting. Circular vein segments were equilibrated under 2 g of tension in a tissue bath, and changes in isometric constriction in response to angiotensin II (AngII, 10(-11)-10(-7) M), phenylephrine (PHE, 10(-9)-10(-4) M), and KCl (96 mM) were recorded. The amount of angiotensin type 1 receptor (AT(1)R) was measured in vein tissue homogenate. AngII caused concentration-dependent constriction in control vein (max 35.3 +/- 9.6 mg/mg tissue, pED(50) 8.48 +/- 0.34). AngII caused less contraction and was less potent in proximal (max 7.9 +/- 2.5, pED(50) 6.85 +/- 0.61), distal (max 5.7 +/- 1.2, pED(50) 6.74 +/- 0.68), and varix segments of VarV (max 7.2 +/- 2.0, pED(50) 7.11 +/- 0.50), suggesting reduced AT(1)R-mediated contractile mechanisms. VarVs and control veins had similar amounts of AT(1)R. alpha-adrenergic receptor stimulation with PHE caused concentration-dependent constriction in control veins (max 73.0 +/- 13.9 mg/mg tissue, pED(50) 5.48 +/- 0.12) exceeding that of AngII. PHE produced similar constriction and was equally potent in varix and distal segments but produced less constriction and was less potent in proximal segments of VarVs (max 32.1 +/- 6.4 mg/mg tissue, pED(50) 4.89 +/- 0.13) vs control veins. Membrane depolarization by 96 mM KCl, a receptor-independent Ca(2+)-dependent response, produced significant constriction in control veins and similar contractile response in proximal, distal, and varix VarV segments, indicating tissue viability and intact Ca(2+)-dependent contraction mechanisms. Compared with control veins, different regions of VarV display reduced AngII-mediated venoconstriction, which may be involved in the progressive dilation in VarVs. Postreceptor Ca(2+)-dependent contraction mechanisms remain functional in VarVs. The maintained alpha-adrenergic responses in distal and varix segments, and the reduced constriction in the upstream proximal segments, may represent a compensatory adaptation of human venous smooth muscle to facilitate venous return from the dilated varix segments of VarV.

Management of bypass graft occlusion of lower extremity

To explore the experience of management of graft occlusion in patients with lower extremity bypass grafting. From July 2002 to September 2009, 115 cases of graft occlusion were treated in 64 patients with lower extremity arterial bypass, including medical therapy for 8 cases and redo operations for 107 cases: graft thrombectomy alone for 32 cases, redo bypass operation with prosthetic grafts for 27 cases, graft thrombectomy plus balloon angioplasty for 17 cases, major amputation for 13 cases, graft thrombectomy plus endarterectomy for 10 cases, removal of occluded graft with infection for 4 case, distally bypass grafting with autologous saphenous vein for 3 case, and autologous stem cell transplanting for 1 case. One patient died of acute renal failure during peri-operative period and 3 patients died during follow-up period, 5 patients were lost to follow-up including 2 with medical therapy. The remaining 55 patients were followed up for 4 to 70 months (average 39 months): medical therapy for 8 patients, major amputation for 12 patients (21.8%), and patent grafts after reconstruction in 35 patients (63.6%). For graft occlusions after lower extremity bypass grafting, redo bypass operation and graft thrombectomy plus endarterectomy or balloon angioplasty may produce better early results.